Ancillary (or spectator) ligand-metal coordination complexes (including organometallic complexes) and compositions are useful as catalysts, additives, stoichiometric reagents, solid-state precursors, therapeutic reagents and drugs. Ancillary ligand-metal coordination complexes of this type can be prepared by combining an ancillary ligand with a suitable metal compound or metal precursor in a suitable solvent at a suitable temperature. The ancillary ligand contains functional groups that bind to the metal center(s), remain associated with the metal center(s), and therefore provide an opportunity to modify the steric, electronic and chemical properties of the active metal center(s) of the complex.
Certain known ancillary ligand-metal complexes and compositions are catalysts for reactions such as oxidation, reduction, hydrogenation, hydrosilylation, hydrocyanation, hydroformylation, polymerization, carbonylation, isomerization, metathesis, carbon-hydrogen activation, carbon-halogen activation, cross-coupling, Friedel-Crafts acylation and alkylation, hydration, Diels-Alder reactions and other transformations.
One example of the use of these types of ancillary ligand-metal complexes and compositions is in the field of polymerization catalysis. In connection with single site catalysis, the ancillary ligand typically offers opportunities to modify the electronic and/or steric environment surrounding an active metal center. This allows the ancillary ligand to assist in the creation of possibly different polymers. Group 4 metallocene based single site catalysts are generally known for polymerization reactions. See, generally, “Chemistry of Cationic Dicyclopentadienyl Group 4 Metal-Alkyl Complexes”, Jordan, Adv. Organometallic Chem. 1991, 32,325-153, and the references therein, all of which is incorporated herein by reference.
One application for metallocene catalysts is producing isotactic polypropylene. An extensive body of scientific literature examines catalyst structures, mechanism and polymers prepared by metallocene catalysts. See, e.g., Resconi et al., “Selectivity in Propene Polymerization with Metallocene Catalysts,” Chem. Rev. 2000, 100, 1253-1345 and G. W. Coates, “Precise Control of Polyolefin Stereochemistry Using Single-Site Metal Catalysts,” Chem. Rev. 2000, 100, 1223-1252 and the references cited in these review articles. Isotactic polypropylene has historically been produced with heterogeneous catalysts that may be described as a catalyst on a solid support (e.g., titanium tetrachloride and aluminum alkyls and additional modifiers or “donors” on magnesium dichloride). This process typically uses hydrogen to control the molecular weight and electron-donor compounds to control the isotacticity. See also EP 0 622 380, EP 0 292 134 and U.S. Pat. Nos. 4,971,936, 5,093,415, 4,297,465, 5,385,993 and 6,239,236.
Given the extensive research activities with respect to metallocene catalysts, there is continued interested in the next generation of non-cyclopentadienyl ligands for olefin polymerization catalysts providing attractive alternatives. See, e.g., “The Search for New-Generation Olefin Polymerization Catalysts: Life beyond Metallocenes”, Gibson, et al., Angew. Chem. Int. Ed. 1999, 38, 428-447; Organometallics 1999, 18, 3649-3670 and “Advances in Non-Metallocene Olefin Polymerization Catalysts”, Gibson, et al., Chem Rev. 2003, 103, 283-315. See also U.S. Pat. No. 6,750,345 and International Application No. WO 02/38628. Recently, for isotactic polypropylene, bis-amide catalysts have been disclosed in U.S. Pat. No. 5,318,935 and amidinate catalysts have been disclosed in WO 99/05186. See also U.S. Pat. Nos. 6,214,939 and 6,713,577, and International Application Nos. WO 03/040201 WO 03/091262 for non-metallocene isotactic polypropylene catalysts.
The polymerization of vinylidene aromatic monomers, especially styrene, has proven difficult to accomplish using non-metallocene catalysts. Recently, Okuda and other researchers have reported the results of their investigations, See, Okuda et al., J. Organometallic Chem., 689 (2004) 46364641, Okuda et al., Organometallics, 224, 2971-2982 (2005), WO 2004/078765, Kim, et al., Macromol. Rapid Commun. 2004, 25, 1319-1323, and Proto et al., Macromolecules 2003, 36, 5942-5946. In general, the known processes have been limited to the use of relatively low reaction temperatures and the production of undifferentiated polymers.
Despite the efforts of many workers in the field, a need remains for commercially suitable catalyst systems for the polymerization of monomers, and in particular for the homopolymerization or copolymerization of vinylidene aromatic monomers, especially styrene or substituted styrenes, for the production of polymers having molecular weights high enough for general commercial use, and variable tacticities, at high reaction temperatures. In particular, what is needed is a catalyst or family of catalysts capable of making a range of vinylidene aromatic polymers with differing degrees of stereoregularity that can be controlled by the appropriate choice of catalyst and conditions. A range of product opportunities could then exist, including polymers uniquely suited for preparation via high temperature solution polymerization processes.
Therefore, a need remains for new polyolefin catalysts in general.